


He Came from the Deep

by Lhugy_for_short



Series: Lhugy's Giveaway Round 3 [1]
Category: Final Fantasy XV
Genre: Fluff and Crack, M/M, Octomer AU, Octopus Gladio, Other, Oviposition, Prompto has a horrible wonderful unforgettable undersea adventure, Tentacle Sex, and SMUT, can't forget that
Language: English
Status: Completed
Published: 2018-05-08
Updated: 2018-05-08
Packaged: 2019-05-03 23:28:05
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 5
Words: 6,518
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/14579973
Author URL: https://archiveofourown.org/users/Lhugy_for_short/pseuds/Lhugy_for_short
Summary: When Prompto was a child, he rescued a helpless sea creature at the beach.He never could have predicted that it would come looking for him again - or, when it found him, to be quite so amorous.





	1. The Tide Pool

**Author's Note:**

> For the incredible artist [Mimi19art](http://mimi19art.tumblr.com/) on Tumblr who has an AMAZING FFXV Octomer AU! The request was for some Octomer!Gladio x human Prompto, and... well this was supposed to be less than 1k, but I got carried away and. Well. Here's 7000 words of Promptio Octopus fluff/smut lol.

Like most children growing up inside the protective walls of Insomnia, Prompto had never actually been to the sea. 

The body of water known as the Lucian Sound was arguably the closest. The city was practically surrounded by it, at least according to the maps in his textbooks, but it may as well have been on the other side of the world as far as he was concerned. He considered himself lucky just to catch the scent of the sea on the breeze some days, for traveling beyond the walls was forbidden without permission from the King. 

Or, as it turned out one fateful summer, from the Crown Prince - who just so happened to be in the same grade as Prompto at their school. With his help, their science teacher was able to organize a field trip to the beaches of Cavaugh, and Prompto was one of the first to put his name on the list. 

If nothing else, at least he was bound to get some great photos of the water.

* * *

On the day of the field trip, the blond double- and triple-checked his backpack. Sunscreen,  _ yep _ . Camera,  _ got it _ . Extra memory card,  _ check _ . He was certain this was going to be the experience of a lifetime, and he was determined not to let a single shot go to waste. So while the other kids climbed onto the bus and shoved each other for the best seats, he focused on polishing his camera lens. 

The ride outside of Insomnia wasn’t long, but it was exciting. Prompto watched the massive walls come into view ahead of their bus, so tall that by the time they were passing under the inner arch, he had to tilt his head nearly all the way back to see to the top. Then they were moving through the checkpoints, one by one, until all that stretched out before them were the dusty plains of Leide. 

A sideroad took them along the coast and up to Cavaugh. All the way, Prompto snapped shot after shot of the clear skies reflected blue as sapphires on the open waves. The sea was beautiful,  _ magical _ , he thought, eyes fixed on the endless glittering surface. Far more incredible than he’d ever seen in movies or on TV, and they hadn’t even reached the beach yet. Excitement bubbled up inside him at the thought of touching those crisp waves with his own two hands. 

The winding drive ended with the bus parked right on the sand. Their teacher stepped out first, then directed the children one by one into groups along the beach, right up to Prompto who was the last off the bus. Before she even finished assigning them tasks -  _ find a turban shell, look for crab dens, count the barnacles on the pier _ \- he was already snapping pictures left and right. Everything that entered his frame was new and exciting, colorful and bright as the sun overhead. And it wasn’t long before he was wandering away from his assigned group to seek out even more discoveries. 

About twenty meters from the other children and behind a sandy knoll, he came across a tide pool in the water. There, several large rocks had been washed away to form an inlet, and the receding tides had left the very center deserted, almost an island of water trapped by the land. 

Prompto had heard tide pools were excellent places to find all kinds of life that had been left behind. Excited, he readied the zoom on his lens and crept closer. 

The shallow pool was about the size of a bathtub, just large enough for him to make out the shapes of tiny minnows swimming under the surface. Below them, a miniature coral garden spread out in a burst of color, covered in anemones, sea sponges, and all kinds of breathtaking underwater flowers. The longer Prompto watched, the more the pool seemed to come to life before his eyes.  _ Incredible, amazing!  _ He leaned closer, the shutter of his camera clicking rapidly with shot after shot after shot. 

Something moved suddenly in the shadows of the coral, larger than the other creatures in the pool, and catching Prompto off guard. In his surprise, he jumped back - and realized too late that the strap of his camera wasn’t properly wrapped around his wrist. Panicked, he fumbled for it, unable even to cry out as his fingers grazed the side of his camera and he was forced to watch as it splashed into the pool. 

He couldn’t move. Couldn’t breathe. His camera! His most prized possession,  _ his only friend _ , sank right down to bed of sand below the surface of the water; its screen flickered, sputtered, and went black. 

“No….” 

Shock set in, but only for a dreadful moment. Then Prompto was scrambling up onto the top of the rocks himself, hand dipping into the cold water without hesitation. Minnows scattered and anemones retreated into their homes in a flurry of bubbles. His sleeve was getting soaked, but he didn’t care - he  _ had to  _ reach his camera, had to get it back before it was too late to --!

The same strange creature he’d seen before darted out again from the shadows. It was dark, as dark as the alcove it had been hiding in, and curled its body around Prompto’s camera as if it were some kind of sunken treasure. The blond shrieked. Snatched up the strap and yanked the whole thing out the water, creature and all, to go tumbling back-first onto the sandy beach behind him. 

His camera, and the thing attached to it, landed on his chest with a wet  _ squelch _ . 

“Gross! Give me that back, you…you…!” Now, out of the water and closer up, Prompto could make out the shape of the creature much better. And he nearly laughed when he realized he’d seen it before. “Aww, you’re just a tiny little octopus, aren’t you? What were you doing in that pool away from your family?” 

With a bit of careful effort, he was able to coax the octopus’ tentacles free one by one, and set his damaged camera aside on the beach. What he’d mistaken for some kind of sea monster was, in fact, surprisingly gentle, and fit perfectly in the palm of his left hand. Prompto giggled as the octopus curled and uncurled its hold on each of his fingers, leaving behind tiny pink circles like kisses across his skin. 

“You’re cute, lil’ guy. Wish I could get a picture of you for the scrapbook.” While he spoke, he stroked the fingers of his free hand over the octopus’ bulbous head. He noted the color of its flesh wasn’t actually black like he’d thought, but a deep, ruddish brown, marked here and there in stripes of purple-red. And it was wet, shining and glistening as he maneuvered it under the light of the sun. “Wow….”

“ _ Argentum! Hey, where’d you go? We gotta get back on the bus!” _

Prompto threw a glance over his shoulder to see the heads of his classmates moving along the other side of the knoll. It seemed they’d finally noticed he was missing from the group. “Oh. Sorry, little guy, I’d better get back to my -- “ He stopped before he could say the word  _ friends,  _ and offered the octopus a weak smile instead. “You’d better get going, too. I’m sure your family misses you.” 

The tentacles around his hand uncurled easily the moment Prompto placed the creature in the water at the edge of the beach. It felt a shame to let it go so soon again - and without even a single photo as a momento - but it would also be cruel to try to keep it away from the sea. So he smiled and waved and watched it crawl out toward the depths, wondering if any of his classmates would believe him if he tried to tell them what he’d found. Probably not. 

Best to keep it his little secret. 


	2. The Shadow in the Water

**Summary for the Chapter:**

> Prompto thought he'd learned his lesson about bringing expensive cameras to the beach....

**Notes for the Chapter:**

> BTW here's some side Ignoct! *glub glub* ;)

 

> _Eight years later_

“Ahh, smell that salt air!” Prompto sucked in a deep breath, his bare chest puffing out full to burst in the process. “ _Whoo!_ I can’t believe we didn’t do this sooner, dude!”

“Yeah, well. Don’t blame me. My dad worries too much.” Noctis set down the picnic basket he was carrying and used his forearm to wipe the sweat from his brow instead. Even behind his oversized sunglasses (as black as his swim trunks and the t-shirt he still wore above them), Prompto could see the way he was squinting at the bright light.

At his side, Ignis didn’t miss a beat. Grabbing the basket in his already full hands, he smiled and nudged the prince forward. “Your father is a wise man, Noct. He had good reason to lock down the walls for so many years, what with the war and all the fighting.”

“The war that’s _over_ now, if you remember,” Noctis countered back.

His advisor and long-term boyfriend (though that was known only to a privileged few) nodded wisely. “Of course. I do believe that’s the only reason he gave in to your request for this little excursion.”

The _‘excursion_ ’ had actually been Prompto’s idea. None of them had left the city since the attacks from Niflheim began all those years back, and the recent signing of the peace treaty suddenly had everyone in Insomnia itching to travel again. Prompto had immediately recalled his own last trip beyond the walls back in grade school - to the beaches of Cavaugh along the Lucian Sound - and begged his royal friend to find them a ride out there again.

Their ride had, unsurprisingly, turned out to be Ignis, and the three had set out from Insomnia for a day of sand, sun, and seafood on the grill.

But first, they’d need to pick a good spot.

“I call dibs on the umbrella,” the prince announced as he unrolled his towel and laid it on the flattest part of the beach he could find. Ignis scoffed.

“It’s called a ‘parasol,’ Noct. Umbrellas are for the rain. Here, help me with this table.”

A shrug. “Whatever. You just made that up. If anything, it should be called a ‘sunbrella.’ ‘Least, that’s what I’ll call it when I’m King.”

“King of _semantics._ ” Still smiling, Ignis glanced up from the barbeque table he was unfolding in time to catch a streak of yellow flying down the beach. “Prompto, where are you going?”

“To get some shots!” he waved back. “While it’s still early!”

“Well, don’t wander off too far.”

“Got it!”

“And put on some sunscreen!” He turned back to his task to find the prince had removed his sunglasses, and deep blue eyes were watching him closely. “What?”

“Nothin’. Just…. How come he doesn’t have to work?”

* * *

  

The beach was somehow different than he remembered it. Narrower, perhaps, or maybe he’d just grown a lot since the last time he'd stood here. There was more seaweed choking the shallows, too; a result of too many years left unchecked and unused by tourists, no doubt. Up ahead, the old pier had fallen into disrepair, the wood broken and splintered in too many places to serve much purpose now.

Still, despite the passage of time, the sight of clear waves lapping at pale sand was stunningly beautiful. Prompto knelt down and snapped off a few quick shots of the afternoon sun reflecting on the water. At his feet, a small sand crab skittered out from its den, and he followed that next, laughing as his camera fired away.

The crab disappeared out of sight again all too soon, but there was plenty left to photograph. Including, Prompto noticed with a wide smile, a very familiar outcropping of rocks nearby - in the center of which shone the very same tide pool he’d visited so many years ago.

“Oh, man, I can’t believe this is still here,” he said aloud, excitement getting the better of him as he jogged closer to the rocks. He was glad to find that he no longer had to climb onto them to see clearly into the pool. Pushing himself up onto his toes, he leaned forward and peered easily over the edge, his blue eyes going wide at the explosion of color that greeted him.

Since his last visit, life inside the miniature marine metropolis had apparently flourished. There were fish, shells, and sea stars, as well as a brand new branch of coral starting to grow next to the larger one. Pink and yellow anemones peeked out to see him, as several little crabs - bright green and snapping at pockets of air in the sand - scuttled from side to side. It was, in a word, _picture-perfect_. Prompto couldn’t wait to show Noct and Iggy.

This time, though, before he brought his camera up to start snapping photos, he remembered to fasten it properly to his wrist. “Fool me once,” he grinned, and pressed his eye to the viewfinder.

How many minutes passed, he couldn’t be sure. Prompto was so engrossed in the colorful scenery laid out before him that he barely noticed the sun beating down on his bare back, or even the cool touch of the sea as the tide began to rise again. Foam hugged his ankles, tickled his feet, but he ignored the sensation in favor of _just one more angle, right there, don’t move, little fishy!_

_Click, click, click._

Another sound deeper out in the shoals. Bubbles, gathering on the surface as something _large_ moved beneath.

_Click-click._ “Don’t worry, little dude. I’ll get some of you, too.” _Clickclickclick._

A muffled splashing noise. Shadows coiled under the crests of sea foam, reaching out for the pair of legs planted so vulnerable, so close.

“Aww, you’re a shy one, huh. Come on, gimme a smile, one more for the -- _Woah!_ _What the..!?”_

By the time he noticed the slick, black tendrils curling around his calves, it was too late. There was no time to cry out, to call for help from his friends just on the other side of the knoll. Panic seized him as quickly as the _thing_ that had grabbed his legs, and before Prompto could even decide to scream, he was being dragged into the water and down under the waves, camera and all.


	3. Under the Sea

**Summary for the Chapter:**

> Prompto's been captured by a friendly sea monster. That's not so bad...right?

**Notes for the Chapter:**

> Gladio's design is based on Mimi19art's [reference sketches](http://mimi19art.tumblr.com/post/169679967500/a-sudden-two-day-thing-to-get-this-thing-outhi)!! Please check out their awesome Octomer AU art!

He awoke surrounded by darkness. 

Assuming, of course, he was even awake at all. It certainly felt like he was stuck in a bad dream, from the chill in the air to the cool  fabric of his swim trunks as they clung, soaking wet, to his thighs. Even the sandy texture of the ground he was laying on felt cold, and he shivered to think how long he'd been out in that very spot. 

Slowly, Prompto pushed himself up onto his elbows. Though he couldn’t see his surroundings clearly, he could make out the distant curve of slick, rock walls, and the rough outline of stalactites hanging down from above. A...cave? It sure was dark and creepy enough to be one. But how had he gotten here? He remembered the beach, and the sunshine, and his camera. Then something in the water at his feet and -- 

_ His camera! _ The sudden thought had him bolting upright at once. Clumsily, he felt around in the sand anywhere he could reach. Eventually rolled onto his knees and widening his search, until a glint of dim light against metal caught his attention. He crawled toward it, wrapped his fingers around the shattered case of the limited edition LOKTON, and barely stifled a sob as it fell to pieces in his hands.  _ Ruined _ .  

He was beginning to think maybe cameras and beaches simply weren't meant to be. 

While he continued to bemoan the broken pieces of his most treasured possession, a gurgling sounded at his back. Bubbles rose up from inky black depths, popping against the calm surface of the water and pulling Prompto back to the moment. 

Startled, he whipped around in time to catch the glistening trail of bubbles beelining for the beach - and, by association,   _ right for him _ . 

“W-woah, don’t come any closer!” he shouted, heart leaping into his throat. The sand gave way under his panicked movements, making it impossible to find footing. “I’m warning you! I-I’ve got friends in the Crownsguard!”  

From out of the dark water, shadows appeared. Several of them, long and wet and coiling as they slithered up onto the cool beach. Prompto could see their outline in sharp contrast to the lighter color of the sand, but it was still difficult to count how many there actually were.  _ Three, four, five...wait, is that six? Seven...eight?!  _ And in the center of them all, an even stranger shape rose up out of the water: tall, broad, with what appeared to be shoulders and arms and even a head to top it ll off. A  _ man?  _ Prompto’s mind spun.  _ Just what the hell was going on? _

“S-sir? Excuse me? C-Can you hear me?” Though the figure didn’t stop, it did temper its pace long enough for Prompto to finally struggle to his feet. “Hello? Are you lost down here, too?” 

He did think, for several strange and oddly distorted moments, that the man might be under the attack of those black, coiling tendrils. That whatever they were, perhaps they were hurting him, and that he was in need of rescue. Yet as he drew closer, Prompto realized the horrifying, sickening truth - those tendrils  _ were a part of him _ . Where the human-esque torso ended, the tendrils began, wrapping around him where his hips and legs should have been, and carrying him over the sand like...well.... Like an octopus. A mass of rolling, curling tentacles that crept toward him like something out of a nightmare and  _ shit _ , Prompto really wished he was only dreaming!

One very thick, very  _ real  _ tentacle rose up into the remaining space between them. Even in the dark, Prompto saw the countless rings along the undulating underside -  _ suckers _ , the kind designed for catching prey. He'd seen this before on  _ The Beast Channel _ : octopi snatching up tasty fish in their powerful limbs, then slowly devouring them, bones and scales and all. Last he'd checked, Prompto didn't  _ think  _ he looked like seafood - but then again, who was to say what made the menu of a weird, tentacled fish man, anyway? 

In the face of almost certain doom, Prompto squeezed his eyes shut. 

But the monster didn't go for his face, or even his neck. It took several heartbeats before Prompto felt the cool, slick touch of the tentacle against his trembling fist instead. Gentle, as if stroking him, before curling in a decidedly non-threatening way around his right wrist. Despite his better judgement, he cracked one eye open for a better look. 

The first thing Prompto noticed was that the cave had suddenly grown brighter. Still dim compared to the surface, of course, but everything around him had been cast into a soft, blue glow. The source, he guessed, being the patches of bioluminescent flowers that were slowly floating up to the surface of the lake.  

The second thing he noticed was that the ‘man' had moved a lot closer. In the blue light, Prompto could see that he was smiling, full, dark lips above a sharp jawline. A rough beard grew there, as dark as the long curls of hair on his head, and the thick brows above strikingly gorgeous eyes. 

The third thing (and it was admittedly difficult to tear his attention away from that handsome face) was that the tentacle wrapped around his wrist and forearm was  _ familiar _ . Not just in color - a dark brown that glowed almost purple in the light, striped with unmistakable patterns of black and red - but also in the way it held him. Tender, timid, hopeful. Prompto’s breath left him in a slow gasp. There was no way! It couldn't be…! 

"You're it. You're the one." His voice sounded oddly small even in the short space between him and the octopus man’s mouth. "H-him, I mean. From the tide pool, all those years ago,aren't you?" 

To his surprise - after all, he hadn't expected the creature to actually understand him - it nodded. 

"R-really?! That was really you? But…what happened? How did you…?" Prompto raked a pointed look over the figure before him, from the very monster-like mass of tentacles to the undeniably handsome (and muscular) human end. "I thought you were just a regular octopus."

When the man’s mouth opened and he laughed - rich, bubbling - it again caught Prompto off guard. "I'm no octopus," he explained in a voice that rumbled surprisingly deep and powerful through both of them. "I'm what your people call a ‘mermaid.'"

The blond’s eyes narrowed incredulously.  _ This  _ was hardly how he'd imagined a mermaid to look (not that he'd believed in those, either). For one thing, the dude had  _ tentacles,  _ not a tail; and for another, he was a  _ dude.  _

…Wasn't he? Just to be sure, Prompto reached up with his free hand to tentatively squeeze one of those firm, bare, scarred pecs. And he gulped. "I think you mean ‘mer _ man. _ '"

But that didn't quite feel right, either. Mer-pus? Octo-man? Octomer? Maybe it didn’t matter. He could waste time debating what to call him  _ after  _ he escaped from this cave. Assuming, of course, that his ‘old friend’ was planning to let him leave at all.

"You may call me whatever you like," came that rich voice again, and Prompto couldn't help but notice several  _ more  _ tentacles moving to touch him. "You, my golden-haired angelfish, once saved my life. For many long years I waited for you to return to the sea. To me."

_ Oh.  _ Okay, well that actually sounded kind of sweet, and maybe like he wasn't about to be eaten. Right?

"My true name is Gladiolus, prince of the Amicitia tribe, and I owe you a great debt of gratitude for returning me to my people."

"Aww, hey it's nothing. You sure were a cute little guy, I was happy to help."

Again, those full lips broke into a smile. "To show you my thanks, I have decided to take you to my kingdom, where you will have the highest honor of being my bride."


	4. Where did THAT come from?!

**Summary for the Chapter:**

> If Gladio can't have Prompto beneath the waves, he supposes this sandy cave floor will do just fine.

**Notes for the Chapter:**

> TENTACLE SEX 
> 
> *cough*

"I-I-I-I can't go with you to the bottom of the sea! I'll  _ die _ down there _! _ "

That, of course, being only one of many pressing reasons why Prompto was, now more than ever, certain that he needed to get the hell out of here. The tentacles surrounding him were another, even as they slumped in time with the octomer’s disappointment. 

Honey gold eyes studied him for a moment. "Oh. I hadn't thought of that. I forget that you land creatures have such weak and delicate bodies." In an attempt to demonstrate his point, Gladiolus draped a long, heavy tentacle across Prompto’s chest, then proceeded to pull it off again sucker by sucker. The blond hissed as pink ring-shaped marks were left behind in its wake. "Very well. If I cannot take you back to my palace, then we must simply perform the ceremony here."

_ No, nonono.  _ That was hardly what Prompto had meant! He couldn't go because he was too young to get married, especially to a sea monster! Even  _ if _ the human half of him  _ was  _ incredibly hot…. But that was beside the point, too. He had to get out of here quick, before some weird Justice of the Deep crawled up out of the water and pronounced them  _ man and fish _ .

"U-um, Gladiolus? I'm sorry, but I've gotta get back to my friends now. You think we could maybe… _ not _ tie the knot, and you could take me home instead?"

The octomer chuckled. So deep and genuinely that it sent Prompto’s heart thudding inside the cage of his chest. "My sweet little land guppy. I have spent half my life seeking you out, and I’m afraid I cannot let you go again so easily." 

_ Great _ . Exactly what he'd been afraid of. 

"Over the years, I have turned down countless lovers in the hopes that one day, I would find you again. That we could be together forever, bound by so much more than a life debt." The octomer’s deep voice drew closer, softer and more encompassing at the same time, like bubbles floating out to caress Prompto’s skin. His hands, which were so human-like and yet the same deep purple-brown color as his lower body, moved to touch the blond’s bare chest, and he shivered at their chill. "You have filled my dreams for so long, my pearl. And I absolutely must have you."

What was happening to him? Prompto was finding it increasingly difficult to move his limbs; they'd grown heavy, tired, no longer capable of holding him up. Instead, his legs relied on the thick coil of Gladiolus’ tentacles around them, moving higher and squeezing as they went. 

His head, too, was growing heavy. Words seemed to slither in through one ear and out the other, hard to catch.

"W…what…?" 

"Your name. It must be spoken for the ceremony to work."

_ Huh?  _ "It's Prompto…."

" _ Prompto, _ " the octomer repeated, and the sound of it had him shivering for entirely different reasons. This was crazy. This was  _ not happening _ , how could it be? Like something out of the weird porn he'd watched in high school (and, okay, sometimes recently, too), the tentacles were working their way under the fabric of his swim trunks. Up along his inner thighs, higher and higher until his breath caught in the act.  _ No, not there…! _ But even as Gladiolus brushed against his balls with that slick, dexterous appendage, Prompto couldn't hide his body’s natural reaction. 

"How warm," the voice in his ear hummed. "How soft. Just as I’d dreamed."

"L-listen, I… If I let you do this," Prompto bluffed in as steady a tone as he could manage, certain there was no way he could stop Gladiolus if he tried. "Y-you gotta promise to take me back to my friends immediately."

"Of course. If that is your wish."

_ Okay, then.  _ Prompto swallowed.  _ No big deal. _ After all, how bad could it be? He wasn't exactly averse to the idea of getting felt up, or whatever it was Gladio had in mind. It all seemed so much like a dream anyway, maybe he could just…pretend he was back at home, in his comfortable bed, jerking off to some hentai. Yeah, that could work. 

A cool tendril swiped between the cheeks of his ass, and Prompto’s eyes flew open. 

_ Ah, crap. _

* * *

__

As it turned out, Gladiolus was quite skilled at moving all eight of his tentacles independently and impressively fast. The two that had slithered up inside Prompto’s trunks had retreated again, only to appear at his back in a cradling sort of hold. At the same time, the pair that had been constricting around his legs unwound as well - earning more than a few breathy gasps at the circular marks left behind on delicate skin - and moved south to coil about Prompto’s ankles instead. When he was at last lifted up, he went easily; tumbled back-first onto the cushion of Gladio’s waiting limbs, and gulped as his own legs were spread open to either side. 

"O-oh. That’s…cool. Um, lemme help you with--"  _ My pants, _ was what he started to say, but even before he could form the words Gladiolus had already taken care of the problem. A single tentacle curled up through the leg hole and around the hem of his trunks was enough to rip them off in one swift move. Prompto watched the bright yellow fabric fall tattered to the ground, and knew that there was no longer any turning back. 

Fear, as well as anticipation, dried his throat.

“Gladio...lus….” 

“Say my name again.” That muscular human form slotted perfectly into place between Prompto’s thighs, abs dragging up and over his exposed cock. 

“ _ G-Gladio--!”  _

The weight of the body above him pressed him down, pinning him between both man and monster. A tongue, slick and cool as the rest of him, slid along the curve of Prompto’s throat and the blond felt dizzier, stranger, more excited all at once. Was this the octomer’s magic? Was Gladiolus doing something to his head, or was it his own desire amplifying his need? Without realizing it, Prompto had curled his own pale arms around Gladiolus’ broader, purplish shoulders, pulling him close even as his head tipped back. 

It returned then, that questing pressure against the cleft of his ass. Different from the other tentacles, this one didn’t seem to function as a limb, nor was it covered in suckers like the ones gripping his ankles or curled around his waist. This one was smooth and thinner at the tip, almost like a finger or…. Prompto nearly laughed. Of  _ course!  _ It was the octomer’s  _ dick _ , and Gladiolus intended to fuck him with it, right? That was why it was swirling around his ring of muscles, probing against them ever so cautiously. It all made perfect sense in Prompto’s half-intoxicated state. So much so, in fact, that he decided to hurry things along by offering a little help. 

Gladiolus had attached his lips to the side of Prompto’s neck, busy sucking an impressive bruise into his skin, by the time the blond began moving. Not fast, and only his hips as the larger man’s weight kept the rest of him effectively pinned in place; but it was enough to catch the octomer’s attention again. He pulled away from Prompto’s neck with a  _ pop _ , and stared down into his half-lidded blues as if mesmerized. 

“It’s okay, big guy. You want me? Go for it.” 

Soft mounds rolled down again, grinding hard into the head of the tendril there, and he saw Gladiolus visibly shudder. At Prompto’s back, the tentacles that supported him closed in, gripped his hips and shoulders - for leverage? For lift? And then as the blond turned his face to meet Gladio’s lips with his own, that tendril pushed into him. 

_ Oh…!  _

_ OH GODS!  _

Maybe ‘go for it’ had been a little hasty, Prompto realized, as the octomer had apparently taken that to mean ‘ _ shove the entire thing into the fragile little human’s body in one move _ .’ Prompto’s thighs shook and his eyes went wide, and even with Gladio’s mouth on his he was trying to gasp for air. Still, the length continued to feed into him, pushing its way deeper and deeper into his gut as it coiled this way and that. Filled him up inch by inch until he was clawing at Gladio’s back for mercy. Left him almost grateful for the fog that clouded his senses and eased the shock, if only just enough.

Slowly, it began to slide out of him again. He cried aloud as Gladio’s mouth left his. The tension seeped out of trembling muscles, and with it a single bead of sweat trailed down his face. 

Gladio was there to lick it up in an instant. “You taste of the sea,” he growled, voice rougher than before, more strained. “Delicious. I am so glad you’re mine at last.” 

“W...wha…? Gladio, n-no, wait, hang on, I--!” 

Once more that length plunged into him, faster this time, retracing its steps. Prompto seized up. Shuddered as it stopped, drew back, then nearly screamed as it filled him again. Over and over, until he could no longer keep his head up against the onslaught. 

His overzealous captor was ready to catch him the moment he fell. Cradled by tentacles, surrounded by them,  _ filled _ by them - in that moment, all Prompto could know was Gladio.  _ Gladio.  _ Inside and out, kissing him, fucking him, claiming him. With the shock wearing off, there was only the odd realization that this felt as good as it did weird. His cock was certainly reacting with enthusiasm, which in turn served to encourage the octomer even more. As Gladio leaned down to kiss him again, he sent another tentacle slithering over the blond’s hip to attend his other needs as well. 

No one could have lasted long like that. Cock engulfed in slick pressure, his hole and insides stretched around such impossible weight, it took only seconds for Prompto to burst. He came with a desperate moan between their bodies - but he hardly had time to catch his breath. Gladio, it seemed, was far from finished. 

The rest was a blur of tentacles and constant stimulation. No longer possessing the energy to resist, Prompto could only moan weakly as thick, cool flesh slid into his mouth, his throat. Could only arch his back and shudder as a second length starting to squeeze its way into his ass. Could only roll his eyes back and come for the third (or was it fourth?) time as Gladio stroked his fingers over the taut planes of his stomach, and smiled at the protrusions visible below the surface. 

It might have taken hours, though how many he couldn’t say. At long last, Prompto was aware of an impatient hitching in the octomer’s breath as he neared his own climax. The longest tentacle retreated from the blond’s body (he was almost sad to see it go, as he felt inexplicably empty without its weight) while the second, shorter one widened inside him. 

“ _ Prompto. With this...we are one.”  _

There was a scrape of beard against his throat - Gladio tucking in close - and a groan as his orgasm shuddered through his every, wriggling limb. 

Had Prompto been expecting anything at that point, he might have imagined an unholy volume of thick, sticky cum to burst deep inside his body, waves and waves of it until it had nowhere left to go but back out. And, had he expected that, he would have been exactly right. But there was one thing he hadn’t counted on - the eight small, perfectly round, pearl-colored eggs that Gladio planted inside of him when he came. 

Then the pale goop was gushing out of him and he had to cling to broad shoulders for fear of losing his sanity, too. 


	5. Pearl

**Summary for the Chapter:**

> When all is said and done, Prompto guesses this isn't the _worst_ thing that's ever happened to him...

**Notes for the Chapter:**

> It's a happy ending, I promise ;) Prompto just needs to warm up to the arrangement.

The ceremony, Gladio explained, was complete. Their mating had been successful; Gladio had planted in Prompto the seeds of their union, which in his culture meant they were now bound to each other for life.

To Prompto, who despite Gladio’s help was still struggling to find his land legs again, it all seemed a bit extreme. "Huh," he said, blushing as the octomer’s human hands slid around him for support. "Where I come from, we just give each other rings."

Not that he wasn't…well, perhaps _grateful_ was the wrong word. _Sated._ He'd had several long moments for recovery after the mind-blowing sex with Gladio, _his octopus husband_ (and wow, was that ever going to take some getting used to! _)_ , yet Prompto was still tingling with afterglow. He felt an oddly pleasant sense of fullness, even smiled as he tapped his fingers over the faint distension in his lower stomach. _Eggs_. As crazy as it sounded, he found that he wasn't repulsed by them - or by the tentacles that coiled softly, lovingly around his bare legs as Gladio closed the space.

That broad chest slotted against his back. His husband ( _fine, octo-husband,_ he was definitely going to need more time on that one) kissed the nape of his neck and Prompto shivered, melting back into his touch. "Gladio?"

"Yes, my darling sea star?"

A sigh. "I…really need to get back home. My friends are probably freaking out by now."

"Your friends…are turning into freaks?"

Prompto blew a laugh out of his nose. "It means they're worried. Probably. At least I think they are."

The fingers stroking the curve of his belly slowed to a pause. "Of course, Prompto. You must have so many people who care for you back on land."

"Hmm. Yeah, I do." Though his cheeks reddened to admit it, he could almost picture the panic his disappearance must have caused at the beach - how Noct had probably called in the Glaive to search for him by now, and how Ignis would be struggling to keep them both calm. It was such a comical image that he found himself laughing even as he sunk back into Gladio’s arms. "I wish you could meet them. They'd probably like you, once they got over…well, _you._ "

Cool, soft lips brushed his temple, his cheek, down to the corner of his mouth, and he felt Gladio smile. "Maybe I could. There may yet be a way for this arrangement to work."

_Oh?_ In his arms, the blond turned. Looked up into deep, amber eyes and felt his breath catch at the tenderness reflected in them. Perhaps the most ridiculous thing of all - more ridiculous even than getting whisked away by an octopus and fucked out of his senses in a cave beneath the sea, and _then_ having said octopus lay eggs in him - was the realization that Prompto did, in fact, want to see Gladio again.

After all, there was nothing else on land or by sea that could compare to tentacles like his.

"Once a month, when the moon is bright as a pearl in the sea above, I will go to your beach. Promise me you'll meet me there?"

"Um, yeah. Yeah, sure, I can do that." A flush tinted Prompto’s cheeks, and he smiled. "And, y’know, in the summer I can come more often. Every week, at least."

When Gladio nodded, his entire face seemed to light up with joy. "As often as we can."

"Awesome."

" _Awesome._ "

"So, um. D’you think you can take me back now?"

Gladio laughed. "Certainly, my precious water lily. But first, I have one more gift for you."

* * *

  

He was still naked when his friends found him, floating ashore on a makeshift raft of kelp at sunset. Noct was the first to go charging down the sloping beach toward him, with Ignis and (as predicted) half the Kingsglaive close on his heels. Together, they helped to pull Prompto safely out of the water, where he was swiftly wrapped in a blanket and given over to the prince’s frantic hugs.

“Prom! We were so worried! Where the hell were you, I thought you’d _drowned!”_

“Indeed. He was a wreck, we all were.” Ignis adjusted his glasses, though even behind the frames his relief was easy to read. “What in Eos happened to you? And where are your clothes?”

Prompto didn’t answer right away. _Couldn’t_ answer, because what in Astrals’ names was he supposed to tell them? Where was he supposed to start? And would they even believe him if he tried?

But Noct was looking at him with such concern in his eyes, waiting for some kind - _any_ kind - of answer. Prompto _had_ to give him one.

And so, untangling his left hand from the blankets, he held it up into the brilliant light that reflected off the sea. Watched his best friend’s gaze settle on the hefty prize there - a polished, white pearl set into a perfect ring of coral - and smiled. “Um. Actually, I got married. Pretty weird, huh?”


End file.
